Flour milling process



Oct. 12, 1965 A. v. MARLOW ETAL 3,

FLOUR MILLING PROCESS Filed Sept. 17, 1963 s Sheets-Sheet 1 Oct. 12, 1965 A. V. MARLOW ETAL FLOUR MILLING PROCESS I Filed Sept. 17, 1963 3 Sheets-Sheet 2 STAGE A STAGE E QLAQLZ FFAL STAGE B STAGE B2 P/I P T K F STAQE F R GERMA p OFFAL FIG Oct. 12, 1965 A. v. MARLOW ETAL FLOUR MILLING PROCESS 3 Sheets-Sheet 5 Filed Sept. 17 1963 STAGE D STAGEA EL- K United States Patent 3,211,385 FLOUR MILLING PROCESS Anthony V. Marlow, Wilmslow, and William A. M. Allen, Bramhall, England, assignors to Henry Simon Limited, Stockport, England, a British company Filed Sept. 17, 1963, Ser. No. 309,527 Claims priority, application Great Britain, Sept. 18, 1962, 35 ,441/ 62 3 Claims. (Cl. 241-l1) This invention relates to a process for the production of flour and particularly to an improved cereal flour milling process.

It is an important aim of cereal flour milling processes, and especially of wheat flour milling processes, that the final flour is made entirely from the endosperm content of the grains and that the particles of endosperm are subdivided in such a way that the starch cells, which form the principal constituent of the endosperm, are not ruptured or broken during the process of reduction. To achieve this aim it is usual to employ a milling process of the kind generally known as a gradual reduction milling process in which cleaned wheat grains are broken, purified, classified and reduced to acceptable size, and in which the breaking steps and the reduction steps are accomplished in rollermills, the purifying steps are accomplished by aspirated reciprocating sieving machines called purifiers Which remove free unattached bran flake-s from the mass of broken grain particles, and the classification steps are accomplished in horizontally gyrating multilevel sieving nnits known as plansifters which are arranged to grade the separated particles of the material undergoing processing in accordance with their size so that the classified particles can be accorded such further reduction as their size makes necessary.

It is a known disadvantage of such known processes that during the steps of particle size reduction by known rollermills, some particles of the pure endosperm are flattened without being completely sub-divided so that platelike aggregates of flour particles are formed which may be as large as or larger in superficial area than the unfl-attened endosperm particles from which they are made, and as such aggregates are automatically classified by the plansifters of the system as requiring further reduction, the capacity of the reduction system has to be substantially larger than it would be if the aggregated particles (usually called flakes) had been completely sub-divided.

Various expedients have been tried for overcoming the aforesaid disadvantage, but hitherto such expedients have relied on the use of friction generating means wherein the flakes are sub-divided into flour particles by being subjected to pressure as they are moved relative to one another and/ or to the confining boundaries of the means, but such expedients are all subject to the disadvantage that the disrupting action which sub-divides the flakes is also applied to intrusive impurities such as bran-flakes or wheat-germ pieces which were attached to the endosperm particles fed to the reduction performing rollermill, and causes such impurities to be so sub-divided that a proportion of the particles thereof are able to pass through the flour-separating screens of the plansifters and join the stream of finished flour, thereby reducing its quality.

The object of this invention is to provide an improved and highly efficient cereal flour milling process which is not subject to the disadvantages before described.

According to this invention, a gradual reduction flour milling process of the kind described, is characterised in that there is, in communication with the products outlets of the rollermills of at least each of the first and preferably next succeeding stages of the endosperm particle reduction sequence of the process, a centrifugal flakedisrupter of a kind frequently referred to as a pin-mill 3,211,385 Patented Oct. 12, 1965 wherein the products of the associated rollermill are directed on to a rotor element from which in a substantially airborne condition they are thrown by centrifugal force radially outwards and across the circular paths of a plurality of pin extensions of the rotor. Under the influence of the erratic movements of the supporting air which at any particular instant surrounds them, the individual particles of material are subjected to internal disrupting stresses arising from rapid accelerations due to random rapid changes in their direction of motion as their inertia carries them from place to place in the confused air currents set up by the orbital motion of the pin extensions of the rotor, and also to impact stresses as a result of innumerable high speed random collisions with other rapidly moving particles which are travelling in dif- 'ferent directions; the stress-producing characteristics of the pin-mill being so adjusted that the comparatively loosely-knit flake aggregates are broken down into separate flour particles, leaving the fibrous impurities such as "bran-flakes and germ pieces substantially intact.

The novel and surprising result of the application of our invention is shown by the following example: In a flour mill employing a conventional gradual reduction flour milling process, the products of the A-stoc (sizings) rollermill (i.e., the first stage of the endosperm particle reduction sequence of the process) when classsified, yielded the following: 23% of the total quantity was directed to the flour stream, 2.7% of the total quantity was directed to the =B-stock (1st rniddlings) rollermill, 13.5% was directed to the B stock (2nd quality) rollermill, and 60.8% was directed to the C-stock (2nd middlings) rollermill; but when this stage of the process was converted to the process of our invention by arranging that before classification in the plansifter, the rollermill products were treated in a centrifugal flake-disrupter wherein the said products were fed on to the central portion of a rapidly rotating horizontal disc element having a plurality of vertical pin-extensions of the disc equally spaced near the peripheral boundary of the disc in two concentric circles round the axis of rotation, the treated products of the A-stock rollermill, when classified, yielded the following result: 50.95% of the total quantity was directed to the flour stream, 0.45% of the total quantity was directed to the B-stock rollermill, 2.7% was directed to the B -stock rollermill, and 45.9% was directed to the C-stock rollermill, the increase in flour quantity having been achieved without any significant increase in the proportion of unwanted fibrous impurities or of broken starch cells.

As succeeding stages of a reduction system according to our invention provide results which are comparable to those described above, the total amount of equipment and machinery required for the endosperm particle reduction sequence of a gradual reduction flour milling process so characterised, will for a given flour output, be substan tially less than for a conventional process, so that considerable savings in capital investment can be achieved for new plants, or conversely, the outputs from existing plants can be greatly increased for comparatively small capital outlay.

Referring to the accompanying drawings:

FIGURE 1 is a sectional view of a suitable flake-disrupter,

FIGURE 2 is a flow diagram of the reduction steps of a gradual reduction flour milling process in accordance with the invention, and

FIGURE 3 is a flow diagram in which the known milling process and that in accordance with the invention are compared.

The flake disrupter shown in FIGURE 1 is of a conventional kind known as a Pin-mill that comprises an electric motor 1 on the shaft 2 of which is a boss 3 carrying a rotor element formed of a pair of discs 4 and 5 between which extend a plurality of pins 6 equally spaced near the peripheral boundary of the discs in two concentric circles. The boss 3 and an inner flange 7 on disc 5 form an annular opening 8 through which material, in an airborne condition, is fed from a spout 9 into the space between the discs 4 and 5. The material is thrown by centrifugal force radially outwards and across the circular paths of the plurality of pins 6, where under the influence of the erratic movements of the supporting air, the individual partcles are subjected to internal disrupting stresses arising from rapid accelerations due to random rapid changes in their direction of motion as their inertia carries them from place to place in the confused air currents set up by the orbital motion of the pin extensions of the rotor, and also to impact stresses as a result of innumerable high speed random collisions with other rapidly moving particles which are travelling in different directions. In the process according to our invention, the stress-producing characteristics of the pin-mill are so adjusted that the comparatively looselyknit flake aggregates are broken down into separate flour particles, leaving the fibrous impurities such as bran-flakes and germ pieces substantially intact. The material after treatment passes to the outlet 10.

FIGURE 2 is a flow diagram of the reduction steps of a milling process in accordance with the invention, with a capacity of some 120 tons of wheat per 24 hours. The roller mill units comprising one side of a back-to-back double rollermill of conventional 40 inch type are shown at R and except at stages A, B, and C feed directly into a plansifter unit P constituted by one half of a section (or stack) of sieves in a conventional plansifter. At stages A, B and C, the outputs of each group of rollermill units R are each passed to a respective flake-disrupter K as described in FIGURE 1 before passing to the related plansifter unit 'P.

Endosperm products from the breaking stages of the milling process enter the particle reduction stages from purifiers at the points indicated as Pu and flour is taken from the process at points indicated as F.

The milling process in accordance with the invention reduces the number of rollermill units and plansifter units required for a given output as compared with the conventional milling process. FIGURE 3 shows the flow diagram of FIGURE 2 which has superimposed upon it in broken line the units which are saved so that the full line and broken line diagrams taken together, but with h the omission of the three flake-disrupters K, show the conventional milling process. It will be observed that in a conventional milling process utilising 26 rollermill units and 18 plansifter units a total of 9 rollermill units and 6 plansifter units with associated spouting and conveying equipment, is saved by the improved milling process in accordance with the invention.

What we claim is:

1. A flour milling process of the kind known as a gradual reduction system, in which at least the first stage of the reduction sequence of operations which follow the breaking sequence of operations consists of three steps these being, a first step of subjecting the endosperm particles from the breaking sequence of operations to a milling treatment in a roller mill having smooth rolls, a second step of submitting milled particles from the said first step to flake-disrupting treatment in a centrifugal flake-disrupter wherein the said particles become substantially airborne and are then subjected to such stresses that comparatively loosely-knit flake particles are disrupted into separate smaller particles leaving fibrous impurities such as bran flakes and germ pieces substantially intact, and a third step of classifying the product from the said second step in accordance with particle size by sieving means and directing the resulting separated fractions to appropriate subsequent stages of the reduction sequence.

2. The process of claim 1 in which the oversize particles from the classifying step are subjected to a further milling treatment in a roller mill having smooth rollers, submitting the milled particles to a flake disrupting treatment, and classifying the products therefrom.

3. The process of claim 2 in which the oversize particles from the classifying step thereof are subjected to a further milling treatment in a roller mill having smooth rolls, submitting the milled particles to a flake disrupting treatment, and classifying the products therefrom.

References Cited by the Examiner UNITED STATES PATENTS 2,464,212 3/49 Carter et al. 241-11 X 2,670,290 2/54 Hanser 24l-9 X 2,941,730 6/60 Mertz et al. 241-9 3,001,727 9/61 Block et al. 2419 ROBERT C. RIORDON, Primary Examiner.

I. SPENCER OVERHOLSER, Examiner. 

1. A FLOUR MILLING PROCESS OF THE KIND KNOWN AS A GRADUAL REDUCTION SYSTEM, IN WHICH AT LEAST THE FIRST STAGE OF THE REDUCTION SEQUENCE OF OPERATIONS WHICH FOLLOW THE BREAKING SEQUENCE OF OPERATIONS CONSISTS OF THREE STEPS THESE BEING, A FIXED STEP OF SUBJECTING THE ENDOSPERM PARTICLES FROM THE BREAKING SEQUENCE OF OPRATIONS TO A MILLING TREATMENT IN A ROLLER MILL HAVING SMOOTH ROLLS, A SECOND STEP OF SUBMITTING MILLED PARTICLES FROM THE SAID FIRST STEP TO FLAKE-DISRUPTING TREATMENT IN A CENTRIFUGAL FLAKE- DISRUPTER WHEREIN THE SAID PARTICLES BECOME SUBSTANTIALLY AIRBORNE AND ARE THEN SUBJECTED TO SUCH STRESSES THAT COMPARATIVELY LOOSELY-KNIT FLANG PARTICLES ARE DISRUPTED INTO SEPARATE SMALLER PARTICLES LEAVING FIBROUS IMPURITIES SUCH A BRAN FLAKES AND GERM PIECES SUBSTANTIALLY INTACT, AND A THIRD STEP OF CLASSIFYING THE PRODUCT FROM THE END SECONE STEP IN ACCORDANCE WITH PARTICLE SIZE BY SIEVING MEANS AND DIRECTING THE RESULTANT RESPECTED FRACTIONS TO APPROPRIATE SUBSEQUENT STAGES OF THE REDUCTION SEQUENCE. 